A fill light can be required for an imaging system to capture images in a low illumination environment such as in the night. Existing imaging systems in mobile phones and cameras employ an automatic flash to provide a fill light. First, a conventional lighting is emitted to provide a tentative fill light, and an image quality under the tentative fill light is obtained using an imaging element such as a charge coupled device (CCD) image sensor. Then, parameters such as a focus and an exposure are adjusted in real-time through a computation, and thus an appropriate fill light is provided to capture an image having satisfactory image quality.
Digital devices such as mobile phones and cameras are designed to capture images having the best quality to meet user expectations, and therefore a series of processes have to be performed including providing a tentative fill light, detecting image quality, adjusting a focus and an exposure, providing an appropriate fill light and capturing an image. The series of processes can take a few seconds and significant computational resources are needed.
However, imaging systems of aerial vehicles and robots impose a high requirement on real time imaging processing in performing a continuous imaging. Due to limited computational resources of imaging systems of aerial vehicles and robots, the conventional method of providing fill light is inadequate in view of the large time delay and significant computational resource consumption. Therefore, the conventional method of providing fill light is not suitable for visual imaging systems in aerial vehicles and robots.